We are fortunate to have a very successful potty-training experience (so far), so here is what we did. We noticed about 9 months ago, when he was 26 months, that our son would always pee in the bathtub at night. So, I put the potty chair in his bathroom and slowly but surely convinced him to sit on it for about 10 minutes each night before his bath. At first he wanted nothing to do with it, so I didn't push but I didn't put it away. About once a week we'd ask again if he wanted to try sitting on it. Also, since we was able to follow me I've let him come into the bathroom with me while I've gone to the bathroom so I think he understood that we go potty in the bathroom. Anyway, one day he agreed to sit. A while later, we "caught it" and coincidentally, he peed while he was sitting on the potty. We were ecstatic! The look on his face was priceless, he was so shocked and excited. So we took him to the kitchen for a reward (we use M & M's).
Each night afterwards, we would continue the routine of sitting on the potty before his bath. We also read "Elmo's Potty Time" and "The Potty Book for Boys". At this point, I would never suggest during the day that we try to go potty. I felt it was too early, and I just didn't have the time or patience to get him to sit for upwards of 30 minutes, waiting for pee. He would never sit still for that long, anyway. So this went on for a few months, and he'd pee maybe once a week or once every two weeks, and we would clap and call Grandma and give M & M's. It was really fun. By about July, he began to tell us that he had to go potty at various points during the day, maybe once or twice a week. We would drop everything and rush to the potty, and lo and behold, he would go! I still had him in diapers, though, because to me, we weren't "potty training". And, if I went to change his diaper and noticed it was dry, I'd ask him if he wanted to try but again, no pushing. We were just laying the groundwork.
So this continued for about another month, but now since he'd begun to recognize the sensation of having to go, I began to ask him a few times a day if he wanted to try to go potty. Sometimes he'd say yes, and sometimes no. Sometimes he'd go and sometimes not. But as he began to tell us more frequently that he had to go, and as he began to wake up dry in the morning, I decided to get pull-ups for him to make it easier to get them on and off when he would try. We aren't doing underpants (although we do use them occasionally) because he is taking Miralax and his bm's are really messy and mostly uncontrollable, poor kid. He was really excited about wearing "big boy pull-ups", and you could tell that his pride was growing and growing every time he would have success.
So this brings us to the end of August. We were home visiting my mom, who had thankfully just bought a potty chair for her house the night before. The next morning, she was in the shower and I was still in bed. My son ran into me, naked from the waist down, saying "I used the potty chair and get an M & M!" I went to the chair and there was pee in it! He had done it completely by himself. And since that day, he has only had a half a dozen "accidents". He's even started pooping in the toilet, too, when he is able to. I would have him in underwear now if it weren't for the Miralax.
Now I realize that it is rare for a child to more or less wake up potty trained, and it's taken a lot of patience to get to where we are, but I am proud of the way we did it and I plan to take this approach when our daughter is older. I don't necessarily agree with the notion that a child is "old enough", so therefore it's time to start potty training. Our philosophy was this: This is what potty is. This is where we put it. We celebrate when it happens, and certainly don't get mad or frustrated if it doesn't. Let's follow his lead and try when he wants, and if we give him the tools and set the example, he will try it for himself when he's ready. He trained us, in a way, and I'm more than pleased with the results. And so you know, our daughter was about 8 weeks old when our son started to catch on and we had just moved from another state, so despite the challenges on our part, it can be done if your son is ready. But that's the most important part - he needs to be ready. Make the process available to him and shower him with praise. Congratulations on the birth of your new son! And good luck with everything :)